Wow, The interior looks great!!
We have the same coach, except mine is a 90 and a 36ft and I don't have a Jacuzzi tub!
As you get going please do not hesitate to reach out. There are a couple of concept owners on here and they are the tops! They are so over engineered its wild to play with them. A couple of things about the Concept, Country coach does not have much for documentation on them anymore but get the know Greg Bootes at CC and also Kevin Waite in Junction City Or. They will help you out a ton. Another member who also has a Concept and myself have been working on a spreadsheet for what everything is. Things like the headlights are Ford from and 89-91 Bronco or F150 and etc.
On the volts, I am about 12.6 at idle. if you are looking at the meter on the dash it is not really accurate but if you open up the battery bay and put a volt on it. One lead on pos and one on neg at idle you should have around that 12.5+ mark or at least I do so you might be fine or you might be looking for an alternator soon.
The heating is always a treat to figure out but hopefully you have manuals, if not a couple of us do so we can send you some. As for the 70k that is good and bad. The Gillig chassis can go several hundred thousand miles or more and is designed to do so. so when at 27 year old coach only has 70 it means it sat a lot. Coaches don't like to sit too much, they start growing gremlins.
Anywho reach out if you need help and awesome coach. as you get around to doing stuff, oil change and ATF etc you will get a better feel for everything.